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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to you under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.hazelcast.org.apache.calcite.rel.rules;

import com.hazelcast.org.apache.calcite.plan.RelOptRuleCall;
import com.hazelcast.org.apache.calcite.plan.RelOptUtil;
import com.hazelcast.org.apache.calcite.plan.RelRule;
import com.hazelcast.org.apache.calcite.rel.RelNode;
import com.hazelcast.org.apache.calcite.rel.core.Join;
import com.hazelcast.org.apache.calcite.rel.core.JoinRelType;
import com.hazelcast.org.apache.calcite.rel.core.Project;
import com.hazelcast.org.apache.calcite.rel.logical.LogicalJoin;
import com.hazelcast.org.apache.calcite.rel.logical.LogicalProject;
import com.hazelcast.org.apache.calcite.rel.metadata.RelMetadataQuery;
import com.hazelcast.org.apache.calcite.rex.RexNode;
import com.hazelcast.org.apache.calcite.rex.RexUtil;
import com.hazelcast.org.apache.calcite.tools.RelBuilderFactory;
import com.hazelcast.org.apache.calcite.util.ImmutableBitSet;

import org.immutables.value.Value;

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

/**
 * Planner rule that matches an {@link Project}
 * on a {@link Join} and removes the join provided that the join is a left join
 * or right join and the join keys are unique.
 *
 * 

For instance, * *

*
select s.product_id
 * from sales as s
 * left join product as p
 * on s.product_id = p.product_id
* *

becomes * *

*
select s.product_id from sales as s
*/ @Value.Enclosing public class ProjectJoinRemoveRule extends RelRule implements SubstitutionRule { /** Creates a ProjectJoinRemoveRule. */ protected ProjectJoinRemoveRule(Config config) { super(config); } @Deprecated // to be removed before 2.0 public ProjectJoinRemoveRule( Class projectClass, Class joinClass, RelBuilderFactory relBuilderFactory) { this(Config.DEFAULT.withRelBuilderFactory(relBuilderFactory) .as(Config.class) .withOperandFor(projectClass, joinClass)); } @Override public void onMatch(RelOptRuleCall call) { final Project project = call.rel(0); final Join join = call.rel(1); final boolean isLeftJoin = join.getJoinType() == JoinRelType.LEFT; int lower = isLeftJoin ? join.getLeft().getRowType().getFieldCount() : 0; int upper = isLeftJoin ? join.getRowType().getFieldCount() : join.getLeft().getRowType().getFieldCount(); // Check whether the project uses columns whose index is between // lower(included) and upper(excluded). for (RexNode expr: project.getProjects()) { if (RelOptUtil.InputFinder.bits(expr).asList().stream().anyMatch( i -> i >= lower && i < upper)) { return; } } final List leftKeys = new ArrayList<>(); final List rightKeys = new ArrayList<>(); RelOptUtil.splitJoinCondition(join.getLeft(), join.getRight(), join.getCondition(), leftKeys, rightKeys, new ArrayList<>()); final List joinKeys = isLeftJoin ? rightKeys : leftKeys; final ImmutableBitSet.Builder columns = ImmutableBitSet.builder(); joinKeys.forEach(columns::set); final RelMetadataQuery mq = call.getMetadataQuery(); if (!Boolean.TRUE.equals( mq.areColumnsUnique(isLeftJoin ? join.getRight() : join.getLeft(), columns.build()))) { return; } RelNode node; if (isLeftJoin) { node = project .copy(project.getTraitSet(), join.getLeft(), project.getProjects(), project.getRowType()); } else { final int offset = join.getLeft().getRowType().getFieldCount(); final List newExprs = project.getProjects().stream() .map(expr -> RexUtil.shift(expr, -offset)) .collect(Collectors.toList()); node = project.copy(project.getTraitSet(), join.getRight(), newExprs, project.getRowType()); } call.transformTo(node); } /** Rule configuration. */ @Value.Immutable public interface Config extends RelRule.Config { Config DEFAULT = ImmutableProjectJoinRemoveRule.Config.of() .withOperandFor(LogicalProject.class, LogicalJoin.class); @Override default ProjectJoinRemoveRule toRule() { return new ProjectJoinRemoveRule(this); } /** Defines an operand tree for the given classes. */ default Config withOperandFor(Class projectClass, Class joinClass) { return withOperandSupplier(b0 -> b0.operand(projectClass).oneInput(b1 -> b1.operand(joinClass).predicate(join -> join.getJoinType() == JoinRelType.LEFT || join.getJoinType() == JoinRelType.RIGHT).anyInputs())) .as(Config.class); } } }




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